Lubricating oil pressure alarm system



Sept. 1, 1942. H H. BROWN 2,294,830

LUBRICATING OIL PRESSURE ALARM SYSTEM 'Filed July 12, 194,1

I I 15K Con-rno SHAFT 6 e do I coN'rRoL. sun sun 51 a flzc'ral? H. BROWN. I pm 8M M Patented Sept. 1, 1942 LUBRICATING OIL PRESSURE ALARM SYSTEM Hector H. Brown, Baltimore County, Md.

Application July 12, 1941, Serial No. 402,149

14 Claims.

The invention relates to the circulation of lubricating oil under pressure in the lubrication of machinery, and particularly to an alarm system for calling attention to any drop of pressure which would result harmfully in the absence of prompt attention by the operator.

The apparatus of the invention has been devised and developed in connection with and is illustrated in its application to an internal combustion engine of the Diesel direct reversing type which is used mainly for marine propulsion. While the apparatus is adapted for application to pressure lubricating oil systems in general wherever they may occur, it is of particular advantage with this type of engine which is extensively used for marine propulsion. Up to the present timethe operators of these engines have experienced notable difficulty in the supervision of the lubricating system. Aside from the pressure indicator which is almost universally used with pressure lubricating oil systems the operators of the engines have been dependent for effective notice of oil leaks and loss of lubricating pressure from other causes upon a low pressure alarm which in the entire period of which the circuit is closed operates whenever the oil pressure is below a predetermined minimum pressure. The alarm circuit is controlled by a hand operated switch and, if the alarm system is in circuit throughout the period of operation of I? the engine, the alarm sounds'continuously till the oil pressure has been built up to the pressure at which the alarm is set and because of the drop of pressure, in reversing, it sounds whenever the engine is stopped or reversed and in maneuvering such reversals and stoppage are frequent.

As the operator or engineer, in the majority of such installations, operates the engine under orders conveyed by sound signals from the pilot h'ouse, such unnecessary and frequent alarm signals result in annoyance and confusion making response to orders difficult so that the oil pressure alarm system is most generally out out by the engineer who throws the cut out switch in said system when starting and/or maneuvering and its use when needed thus becomes a matter of memory. The engineer or operator having cut out the oil pressure alarm system for very good reasons, as above stated, frequently forgets to close the alarm circuit after starting or after maneuvering so that, when needed, the alarm is not operatively connected and a leak in the lubricating oil line or a broken lubricating oil pump results in burned bearings, loss of time and services of the machine or ship and a large repair bill. While a light signal may be substituted for the bell and a red light has been used to show when the signal is disconnected, the lights are frequently unnoticed and if the light bulbs become burned out they give a false indication of security.

An accomplishment of the present invention is the provision of a lubricating oil pressure alarm system, the operation of which is continuous throughout the operation of the engine or other machine to which the lubricating system relates and of which it is a part so that. it is not subject to the human element or otherwise expressed is foolproof. It is of particular importance that the improved alarm system of the invention does not sound or signal except in instances in which there is a loss of pressure due to some leak or defeet in the lubricating oil system. While the alarm system of the invention is capable of more general application, the improved alarm system is of particular advantage in supervising the lubrication of direct reversible Diesel engines, par-. ticularly in marine propulsion, and it, in fact, represents the solution of a difiicult problem which has been studied unsuccessfully for a long period by operators, engineers and designers of such equipment.

Features of the invention which are regarded as of primary importance in the solution of the problem involved include a delay device which prevents the sounding of the alarm for a period sufiicient to build up the lubricating pressure,

and, second, the operative connection of the master switch of the alarm system to the machine or engine being lubricated so that the alarm circuit -is opened and closed as the machine is changed from operative to inoperative condition and vice versa. The delay may be accomplished by various means providing for and/or dependent on the building up of pressure above that at which the alarm sounds and the master switch may be otherwise operated.

In the accompanying drawing I have illustrated diagrammatically an alarm system embodying the features of my invention in the preferred form, the same being shown in connec-, tion with a Diesel motor of the direct reversing type and in connection with the lubricating oil pressure system of such motor.

Referring to the drawing by numerals, the i1- lustration includes a Diesel engine of the direct reversing type most generally used for marine propulsion and similar purposes, the same being indicated by reference character I. This engine is provided with an oil pressure lubricating sys.

tem including any suitable type of oil pump 2 which is connected by a pressure pipe 3 from any part of the lubricating system or direct from the pump 2 to an expansion chamber or diaphragm chamber 4 which controls in any suitable manner as by way of sliding rod 5, the high-low pressiue switch unit 6 and particularly switch lever 6' which engages alternatively a pair of low pressure on the opposite side of the switch lever B from low pressure contacts and 8.

The expansion chamber or diaphragm chamber 4 would in practice be provided with an operating pressure adjustment. A satisfactory position of said adjustment would provide for contact of the switch lever B with the high pressure contact member or terminal I2 at and above a pressure of five pounds and for contact with the low pressure terminals 1 and 8 at a slightly lower pressure. Any desired pressure may be selected within the operating scope of the system which will give the engineer time to stop after an alarm and before the system is sumciently drained to result in damage to bearings, etc. When the engine is not running the switch lever 6' would be in the position shown.

Inaddition to the high pressure switch terminal |2 the delay feature of the alarm system, in the preferred form, includes an alarm switch unit indicated in a general way by reference character l5 and an alarm switch I! in circuit with the horn and controlled by the high-low pressure switch unit 6. The alarm switch proper includes moving switch member I! and terminal IT.

The alarm switch unit l5 consists of an alarm magnet l5 having its armature 4 mounted on a sliding rod I3 which is shown as carrying at its lower end the switch member I! in the path of which in the stationary condition of the engine as shown is an armature 22 or other detent controlled by the magnet 2| or other suitable delay means dependent for its operation on the build up of the pressure in the lubricating system.

The delay feature may be of any suitable type,

fluid pressure operated, mechanically operated, or electrically operated, various methods of op-- eration being feasible. This delay unit 23 is in the form of an electromagnet, having an armature 22 or detent mounted in any suitable manner as on the sliding rod 24 being normally advanced into the path of the switch I! by the spring 25. A guide for said sliding rod 24 is shown at 25.

The engine is controlled by a wheel 21 which determines and times the starting, stopping and I? reversal of the engine. This wheel is mounted on and operates shaft 23 which, in practice, controls an air starter, a fluid supply and the position of the valve shaft, all of which is regular practice in the construction of this type of Diesel engine.

For convenience in the diagrammatic illustration of the alarm system, a section of the shaft 28 has been transferred downwardly from the engine, the same being indicated by reference character 28. This member 28 may be regarded as a portion or extension of this shaft 28 removed and transferred downwardly for convenience of illustration.

The section of the shaft 28 at 28' may be provided with an arm 29 rigidly secured thereto to rotate therewith and projecting radially therefrom. This shaft end or section 28' is shown as connected by a conductor or electrical connection 39 to the plus terminal 9 of the source of electricity, and the arm 29 carries a moving contact member 3| which engages a contact are 32 including two contact segments 33 and 34 corresponding to the forward or starting and reverse positions of the wheel 21. The segments 33 and 34 are spaced apart leaving a short are 35 which may be covered with non-conducting material and in which the contact member 3| is out of electrical contact With segments 33 and 34 and the circuit is broken, said position of shaft end 28' and arm 29 corresponding to the neutral or stop position of the wheelZl in which the engine is inoperative or-stationary. The forward segment 33 and the reverse segment 34 are connected by conductors indicated by reference characters 31 and 38, to the delay magnet 2| and to the low pressure plus contact 8. The low pressure switch, i. e., the negative terminal 1 thereof is connected by a conductor 39 to the ground or minus terminal of the source at H].

The terminal 49' of the magnet 2| is connected by a conductor 49 to the high pressure terminal |2 of the high-low pressure switch 6.

The alarm magnet l5 of the alarm unit I5 is connected by a conductor 4| to the conductor 31 and is in circuit whenever the master switch 3|, 32 is closed. Terminal or contact ll of alarm switch I1 is connected by conductor 4| to conductor 31 and hence to switch 3!, 32. Switch I1 is connected by a conductor 42 to the horn terminal 43. The minus terminal of the horn at 44 is connected by conductor 45 to the conductor 38 which leads to and through the low pressure switch terminals 8, 1, to and by way of conductor 39 to the minus terminal ID of the current source or to ground.

The other or minus terminal 46 of the alarm magnet I5 is connected to the minus terminal ID (if the source or to the ground by a conductor 6.

When the arm 29 carrying the contact 3| is in center position in which the latter is in or on the non-conducting or other stop section 35, the alarm system receives no current and is inoperative so that the horn or other signaling device does not sound. In this position of contact 3|, the engine is inoperative. If the control wheel 21 and contact 3| remain in this position the engine will continue to be inoperative and the pressure in the oil system will drop to zero and low pressure contacts I, B, will be engaged by lever 6 but the alarm being inoperative having its circuit broken the horn will not sound. This frequently happens in maneuvering. On the other hand, the engine may be quickly reversed, contact 3| passing quickly over segment 35. At such times the pressure may not drop to five pounds and there is no functioning of the alarm. On moving the wheel 2'! to the forward position in which the arm 29 on the shaft end 28' moves the contact member 3| to the contact arc 33 marked forward, the engine starts and almost immediately the oil pressure in the lubricating system builds up and the diaphragm chamber 4 is expanded the oil pressure rising to any amount to which the dia phragm chamber 4 may be adjusted. The switch arm 6' thus leaves the low pressure contacts 1 and 8 and engages the high pressure contact |2. The delay magnet 2| is thus placed in circuit, the armature 22 thereof is drawn toward the magnet, and the path of the switch I1 is thus unobstructed. This operation responds to the building up of operative pressure in lubricating system and may be accomplished responsively thereto in any convenient manner, mechanical, electrical, or fluid pressure operated. The control switch 3|, 32, 33, 34, 35 for the alarm circuit may be hereinafter referred to as the master switch, being the switch relied upon to place the signalling system or alarm system in or out of circuit when the engine is started and stopped.

The electromagnet referred to as the alarm magnet I is already in circuit through the connections 31, 4|, 46 and when armature 22 or other latch or obstruction is moved out of the path of switch H, the armature I4 is moved downwardly by attraction of magnet l5 and the switch |1 contacts the terminal l1 closing the circuit to the plus terminal 43 of the horn through the connections 31, 4|, |1', I1, 42, 43. The horn circuit is, however, broken at 1, 8, the switch arm 6' being out of contact with the low pressure terminals 1, 8 and the alarm is inoperative. The system remains in this condition as long as the motor is running provided lubricating oil pressure is maintained. If there should be a break in the oil line or stoppage therein or failure of the oil pump or insufiicient oil supply, the pressure will drop, the switch arm 6' will swing into contact with low pressure terminals 1, 8, of the highlow pressure switch 6 and the alarm circuit being completed, the alarm will sound. The switch being set at approximately five pounds, or any suitable pressure, the operator or engineer will have time to move the wheel 21 to stop the engine and prevent damage before the lubricating oil system is drained, and/or the smooth contacting surfaces injured.

When and if, in maneuvering, or at any time, the wheel 21, shaft 28 and its end section 28' and arm 29 are moved to a position in which contact 3| is between forward and reverse so that the segment 3| passes out of contact with energized segments 33 and 34, the alarm system is electrically disconnected, the spring 25 returns the armature or detent 22 to the position in which it is shown, the magnet 2| being de-energized, also the pressure having dropped, the switch arm 6 of the high-low pressure switch will return to the low pressure contact and the circuit will be opened at l2, also the switch |1 will be opened as the armature I1 is withdrawn upwardly by spring I3 so that the system is ready to repeat its operation, detent 22 having moved under switch H by spring 25.

The invention thus provides an arrangement which may be applied to various machines though particularly adapted to direct reversing engines, the alarm system is de-energized whenever the machine is stopped or reversed and immediately thereafter regains its operative condition as soon as the pressure builds up sufiiciently to close the high-low pressure switch 6, as by contact of the arm 6' with the high pressure terminal l2. When this happens the delay magnet 2| or other delay device having been operated or energized its armature 22 or other deterrent is withdrawn from the path of the switch l1 which immediately closes so that the system is ready to operate whenever the pressure drops, closing contact at 1, 8.

As already suggested the two operating contacts 33 and 34 are not necessary to the operation of this alarm system but are found to be of advantage when it is applied to a Diesel or other fluid pressure type of direct reversing engine.

Instead of being mounted on the control shaft 28 having forward, reverse and neutral or inoperative positions determining three different periods of motor operation, to which control shaft the master switch 3|, 29, of the alarm system is connected to be operated by said shaft to determine the corresponding operative and inoperative periods of the alarm system, the master switch controlling the operative and inoperative periods of the alarm system may be mounted on or connected to any part of the machine or engine thus lubricated, which part has a position corresponding to the inoperative or stationary condition of said machine or engine and one or more positions corresponding to its operative condition or conditions.

It is regarded as important though not essential to the operation of the system that the alarm be placed in circuit when the machine lubricated is started and rendered inoperative when it is stopped and further it is essential that the alarm system have a delay means or detent which prevents sounding of the alarm during the period when the pressure is building up to operative condition. This may be determined by timing or pressure.

It is also important to note that there is no sounding of the signal on starting because the circuit is initially broken at !1 and does not close at this point until the pressure is sufficient to make contact of the high-low pressure switch arm 6 with high pressure terminal I2.

In case of a leak in the system which may have drained the oil while the engine is idle, the pressure would not build up on starting, there would be no contact at I2 and the switch l1, l1 remaining open the horn would not sound even in the complete absence of pressure in the lubricating system.

To overcome this difiiculty a thermostatic switch 553 which may be of the bimetallic variety has been provided which is connected to the plus side of the line at 38' and which has a heating coil at 5| in the connection 38 to the low pressure switch, the contact 54 of this switch, is connected by conductor 52 to the plus terminal of the horn at 43. The passage of the current through the low pressure terminals 8, 1, for a predetermined. period as thirty seconds thus raises the temperature of the coil 5| so that contact is made between switch 58 and its contact 54, sounding the horn and notifying the engineer of the absence of lubricating oil pressure in the system. in time to enable him to stop the engine and look for the source of the difficulty before any damage has been done. Member 55 indicates a compensating arm that may be provided to prevent contacting of the switch 56 due to excessive temperatures in the engine room. Adjustments 56, 51, 58 provide for change of timing both for change of temperature in the engine room, viscosity of the oil and different viscosities of difierent oils.

I have thus described my invention in what may be regarded as the preferred form, and the manner of constructing, applying, operating and using the same, the description being specific and in detail in order that practical application of the same may be fully understood; however, the specific terms herein are used in a descriptive rather than a limiting sense, the scope of the invention being defined in the claims.

What I claim as new and desire to secure by Letters Patent is:

1. The combination with a machine having an oil circulating system and a pump operatively connected to the machine for applying pressure to the oil in said system, an electric circuit and a signalling unit in said circuit, circuit closing means and means whereby said latter means is controlled by the pressure in said system tending to close the circuit through said unit at and below a predetermined low pressure in said system, a master switch in said circuit and means connected to said machine having a plurality of positions corresponding respectively to the operative and to the inoperative conditions of said machine, said master switch being connected to and controlled by said latter means whereby the master switch is closed when the machine is in operative and opened when it is in inoperative condition and delay means controlling said circuit holding said circuit open and preventing operation of the signalling unit at the time of starting said machine, and until pressure in said lubricating system is built up to a point above said predetermined low pressure and means in said circuit for operating said signal in case of excess delay in building up the oil pressure in starting.

2. The combination with a low pressure alarm and alarm actuating circuit for the lubricating oil circulating system of a machine, said system including means connected to the machine for building up oil pressure in the circulating system, of an oil pressure actuated member connected to the said system and carrying a switch member, a low pressure terminal in the alarm circuit cooperating with said switch to control the alarm, said circuit having a high pressure terminal which is adapted to be contacted and included in the circuit, as the low pressure switch is opened, and vice versa, a magnet in circuit with said latter terminal and a detent controlled thereby, an alarm switch in said circuit and an alarm magnet in said circuit tending to close said latter switch, means connected to the machine to close the alarm circuit as the machine is started and to open said circuit as the machine is stopped, said detent being normally in the path of the alarm switch to be withdrawn when its controlling magnet is energized.

3. The combination with a low pressure alarm and circuit for supervising the pressure in a lubricating oil circulating system of a machine, having means for establishing and maintaining pressure in said system of a master switch in said circuit connected to the machine, to be closed when the machine is placed in operation and opened when the machine is stopped and means for delaying operation of the alarm after the closing of the master switch until the lubricating oil pressure is built up above said low pressure, and circuit changing means timed by said delay means and providing for immediate operation of the alarm on the reduction of said lubricating oil pressure to said low pressure occurring while said circuit is closed at said master switch and subsequently to said building up of pressure.

4. The combination with a low pressure alarm and circuit for supervising the lubricating oil circulating system of a machine having means for establishing and maintaining circulating pressure in said system, of a master switch in said circuit connected to the machine to be closed when the machine is placed in operation and opened when the machine is stopped and means for delaying operation of the alarm after the closing of the master switch thus providing for building up of pressure above said low pressure, said delay means comprising a high pressure control for said circuit having a pressure operated element connected to the oil system whereby said control is operated at a pressure above said low pressure, a magnet energized by said high pressure control and a detent actuated thereby, a normally open alarm switch in the alarm circuit, an electro magnet controlled by the master switch tending to close the alarm switch, said detent engaging the alarm switch to prevent its operation and being withdrawn when said high pressure control is operated.

5. The combination with a low pressure alarm and circuit for supervising the lubricating oil circulating system of a machine, a master switch in said circuit and connected to the machine to be closed when the machine is placed in operation and opened when the machine is stopped and delay means for preventing operation of the alarm for a period after the closing of the master switch thus providing for building up of oil pressure above said low pressure, said delay means comprising a high pressure control for said circuit and a pressure element connected to the oil system and operating said control, a magnet energized by the closing of the high pressure switch and a detent controlled by said magnet, a normally open alarm switch in the alarm circuit, an electro magnet controlled by the master switch and tending to close the alarm switch, said detent controlling the alarm switch to prevent closing thereof and being withdrawn when said high pressure switch is closed, a time switch in said circuit and adapted to lead current to the alarm, the same being in parallel with the high pressure contact to sound the alarm if pressure does not build up within a predetermined period after starting said machine.

6. The combination with a low pressure alarm and circuit for supervising the lubricating oil system of a machine said circuit comprising a low pressure contact in said circuit, of a high pressure contact also in said circuit, pressure controlled means closing said low pressure contact below a predetermined low pressure and opening said low pressure contact and closing said high pressure contact at a higher pressure, said alarm circuit having a master switch for controlling said circuit and connected to said machine to close the alarm circuit on starting the machine and to open said circuit on stopping, an alarm switch controlling the sounding of said alarm and normally open, a magnet controlled by said master switch for closing the alarm switch, a detent normally restraining said alarm switch from closing and means controlled by said high pressure contact adapted to withdraw said detent from engagement with said alarm switch when the high pressure contact is closed.

7. The combination with a low pressure alarm and electric circuit for operating the same in supervising the lubricating oil system of a machine, having means for building up and maintaining oil pressure in said system, said circuit including a low pressure contact which, when made, tends to sound the alarm, a high pressure contact and means controlled by the pressure in said system for selectively closing the low pressure contact below and the high pressure contact above a predetermined pressure in said system, said alarm circuit having a master switch for controlling said circuit, an alarm switch controlling the sounding of said alarm and normally open, a magnet controlled by said master switch, a detent normally restraining the alarm switch from closing and means timed by the closing of the high pressure contact for rendering said detent inoperative.

8. The combination with a low pressure alarm and electric circuitior operating the same in supervising the lubricating oil system of a machine, having means for building up and maintaining oil pressure in said system, said circuit including a low pressure contact which when made tends to sound the alarm, a high pressure contact and means controlled by the pressure in said system for closing the low pressure contact below and the high pressure contact above a predetermined pressure in said sytem, said alarm circuit having a master switch for controlling said circuit, an alarm switch controlling the sounding of said alarm and normally open, a magnet controlled by said master switch for closing the alarm switch, a detent normally restraining the alarm switch from closing and means timed by the closing of the high pressure contact for rendering said detent inoperative, and a time switch in the circuit with the alarm and controlling the same to operate the alarm when the said alarm switch fails to close, the low pressure contact remaining closed for a predetermined period after the machine is started, the master switch being closed.

9. The combination with the lubricating oil system of a fluid pressure engine of the direct reversing type having means for applying pressure to the oil in said system of a low pressure alarm and alarm circuit for indicating harmful loss of pressure in said system of a master switch controlling said system and connected to said engine to close the switch when the engine starts and to open it when the engine is stopped, said circuit including a high pressure switch tending to delay operation of the alarm, pressure means for closing the said latter switch and at the same time opening the low pressure switch at a pressure above said low pressure and vice versa, circuit changing means controlled by said high pressure switch whereby on closing of the high pressure switch the circuit is placed in condition for immediate operation of the alarm on loss of pressure and closing of said low pressure switch while the master switch is closed.

10. In a protective circuit for the oil pressure lubricating system of a machine, a high-low pressure switch, an electrically actuated protective unit, means connected through said switch when closed on the low pressure side, for energizing the protective unit, delay means normally operative to prevent closing of the circuit through said protective unit, said delay means being connected in said circuit to be controlled by completion of the circuit through the high pressure contact of said high-low pressure switch, when closed on the high pressure side, to be energized normally permitting closing of the circuit through said protective unit when and only when the circuit has first been made on the high pressure side of said high-low pressure switch, subsequent loss of pressure and closing of said high-low pressure switch on the low pressure side serving to connect and actuate said protective unit.

11. In a protective circuit, for the oil pressure lubricating system of a machine, a high-lowpressure switch, an electrically actuated protective unit, means connected by closing of said switch on its low pressure side for energizing the protective unit, delay means normally operative to prevent the closing of the circuit through said. protective unit, said delay. means being connected to said circuit through the high pressure contact of said high-low pressure switch when closed on the high pressure side, to be energized, normally permitting closing of the circuit through said protective unit when the circuit has first been made and broken on the high pressure side of said high-low pressure switch, subsequent loss of pressure and closing of said high-low pressure switch on the low pressure side serving to connect and actuate the said unit, a master switch controlling said circuit and connected to the machine to be closed when the machine is started and opened when it is stopped and means automatically returning the circuit to normal when the machine is stopped.

12. In a protective system for the oil pressure lubrication of a machine, a, high-low pressure control connected to the oil pressure of said system, a protective unit, delay means normally preventing the actuation of the protective unit, the same being connected to said control to be actuated when operating pressure is applied to said control thus timing the actuation of the protective unit to take place after operating pressure has been reached, means for actuating said protective unit connected to said control to be operated when and only when the pressure applied to the control drops below a predetermined operating pressure after said delay means has been operated by previous application of operating pressure at the control, means connected to the machine thus lubricated for placing the protective system in operation when the machine is started and means for returning it to normal when the machine is stopped.

13. In a protective system for the lubricating oil pressure of a machine, a high-low pressure switch having a pressure controlled member connected to the lubricating oil pressure, a moving conductor operated by said member and connected to the circuit, and high and low pressure contacts to be alternately engaged by said conductor at pressures respectively at and below the predetermined operating pressure, a protective unit connected to the low pressure contact of said switch, to be energized therethrough on completion of the circuit through said conductor and said low pressure contact of the high-10W pressure switch, and delay means for timing the completion of the circuit through said protective unit and said low pressure contact, said delay means being connected to the high pressure contact and operated therethrough to prevent closing of the circuit through the protective unit and the low pressure contact until the high-low pressure switch has first been closed on the high pressure side and thereafter closed on the low pressure side.

14. A protective circuit for the lubricating oil pressure system of a machine comprising a highlow pressure switch connected to and operated by the oil pressure, delay means comprising a delay relay, including a switch, an electrically operated protective unit, electrical connections tions including the switch of said relay when closed, and the low pressure contact of said high-low pressure switch when closed on the low pressure side, the coil of said relay havin connections fOr energization including the high 5 pressure contact of said high-710w pressure switch and means preventing closing of the delay relay switch until the circuit is closed at the high pres- 

